Construction:Two-magnetic circuit lifters have strong magneitc path by NdFeb magnetic materials.On and off the magnetic path is controlled by turning the manual nozzle.Higher magnetism.less weight and less remaining magnetism when being off,which makes a more reasonable structure.Especially for handle,its new designs enable its damper strength on operating is only 30%-40% compared with the single-magnetic ones.Thin magnetic-inductive material can also be lifted as long as their thickness is more than 5mm.As a result,they are in a more widely use than single-magnetic circuit lifters. Safety factor:3:1